Antimony thin films of different thicknesses have been vacuum-deposited onto cleaned glass substrates held at room temperature, and their thermoelectric power and electrical resistivity have been evaluated as functions of temperature and thickness. The Jain-Verma theory of the size effect on the thermoelectric power of thin films has been applied to the experimental data to understand the nature of the scattering mechanism in antimony thin films. The carrier mean free path Ig and the Seeback coefficient Sg of the bulk (with thin film microstructure) have been evaluated at room temperature from the resistivity-thickness and thermoelectric power-thickness plots, respectively, as 1200 Å and 30.1 μVK-1. Using these values Sf/Sg, the thermoelectric power of the films (in the units of Sg, as given by the Jain-Verma theory has been plotted as a function of thickness t/Ig (in units of Ig) for different values of the scattering parameter b to generate a family of curves. By finding out on what curve or curves the experimental thermoelectric power values lie, the scattering parameter has been evaluated to be -0.2, so that the relaxation time τ varies as τ=a E-0.2 in antimony thin films. It is inferred from this that the major scattering process in our antimony thin films is lattice scattering even though other scattering processes also occur to a lesser extent in the films in the temperature range studied. © 1990.